(a) Field of the Invention
The present invention relates to a display device and a driving apparatus thereof.
(b) Description of Related Art
A liquid crystal display (LCD) includes a pair of panels provided with pixel electrodes and a common electrode, with a liquid crystal layer having dielectric anisotropy interposed between the panels. The pixel electrodes are arranged in a matrix and connected to switching elements such as thin film transistors (TFTs) such that they receive image data voltages row by row. The common electrode covers a surface of one of the two panels and is supplied with a common voltage. A liquid crystal capacitor is formed by the pixel electrode and corresponding portions of the common electrode, as well as the corresponding portions of the liquid crystal layer. The liquid crystal capacitor and a switching element connected thereto are the basic pixel elements for the device.
An LCD generates electric fields by applying a potential difference between the pixel electrodes and the common electrode. The strength of the electric field in regions of the liquid crystal material alter the transmittance of light passing through the regions of the liquid crystal layer. By applying appropriate potential differences across each of the pixel regions, images are displayed.
Recently, LCD designs incorporating sensors have been developed. The sensors sense a change of pressure or incident light caused by a touch of a finger or a stylus. The sensors provide electrical signals corresponding to a sensed touch to the LCD. The LCD determines whether and where a touch exists based on the electrical signals. The LCD sends information indicative of a sensed touch to an external device, which may generate and return image signals to the LCD based on the received information. Although the sensors may be provided on an external device such as a touch screen panel to be attached to the LCD, doing so may increase the thickness and the weight of the LCD, and may make it difficult to represent minute characters or pictures.
A sensor incorporated into an LCD may be implemented as a thin film transistor (TFT) disposed in a pixel displaying an image.
Additionally, available sensor configurations may not be optimal for some types of devices. LCDs including a sensor array require a sensing signal processor that is continuously reading signals from the sensors when the LCD is powered, thereby continuously consuming power. Accordingly, the power consumption of the LCD may be increased by employing the sensors and the sensing signal processor. This may be problematic for portable devices incorporating LCDs (such mobile phones and personal digital assistant (PDA) devices) which require low power consumption.